I changed the coolant in my Vectra (3.2 V6) yesterday – but I’m not convinced that I did it right. In my previous car I would change the coolant by removing the lower radiator hose and then flushing the block via the heater hose and heater core.
I tried a similar approach on the Vectra, except that was unable to remove the heater hose (despite removing the hose clamp) and was reluctant to force it. Instead I flushed the block by putting a garden hose first in the reservoir and then up the bottom radiator hose. All the subsequent water that run out of the block and radiator seemed to be clean.
However, it seems that about half of the capacity of the cooling system remains in the block despite the remove of the lower radiator hose. Therefore, after the flushing, I simply refitted the bottom radiator hose and added 3.85 litres of undiluted red coolant to the reservoir, with the assumption that this would combine with the clean water in the block to achieve the 50/50 ratio. Anyway I took the car for a 20km spin (with a container of 5 litres of water just in case) and all seemed fine. The next morning I checked the reservoir and it was slightly below the cold mark and adding about a cup of water bought it up to the correct level.
I am concerned whether I really did manage to flush the block properly using my dilution technique. And what about the old coolant that remained in the heater hoses and core – is this an issue? Even if I had managed to remove the heater hose in order the flush the heater core, how does one ensure that the heater valve is open in a car with climate control?
I would really appreciate people’s thoughts on this. Cheers!